1. Field of the Invention
This invention generally relates to a bicycle derailleur. More specifically, the present invention relates to a bicycle derailleur having a linkage assembly operatively disposed between a base member and a movable member that reduces an operating force during a movement range of the movable member with respect to the base member.
2. Background Information
Many bicycles are provided with a drivetrain that allows the rider to changing a gear ratio for transferring power from the pedals to the rear wheel. Often, in a drivetrain that has a chain extending from a front crankset to a rear cassette, the drivetrain sometimes uses one or more derailleurs to change the gear ratio. A front derailleur is mounted to the bicycle frame adjacent to front chain rings to shift a chain laterally between the front chain rings. A rear derailleur is mounted adjacent to a hub of the rear wheel to shift the chain laterally between rear sprockets. In either case, the derailleur typically includes a fixed or base member that is non-movably secured to the bicycle frame and a movable member. The movable member typically includes a chain guide that is movably supported relative to the base member to move between at least two lateral shift positions. Typically, a linkage assembly is coupled between the base member and the movable member in order to movably support the movable member with the chain guide. The derailleur is typically operated by an operation cable that is coupled between a shifter and the derailleur.